Method of synthetic-resin manufacture



rates-tea Aug. 19, 193.0 1,773,598

- UNITED STATES PATENT OFFICE 'EMIL E. NOVOTNY, F LOGAN, PENNSYLVANIA, ASSIGNOR TO JOHN'STOGDELL STOKES, OF SPRING VALLEY FARMS, HUNTINGDON VALLEY P. 0., PENNSYLVANIA.

METHOD OF SYNTHETIC-RESIN MANUFACTURE No Drawing. Original application filed August 5, 1926, Serial'No. 127,482. Divided and this application filed August 12, 1927. Serial No. 212,607.

This invention relates to plastics and plastic compositions and the process of making the same. It is more particularly directed to the production of synthetic resin condensation products of xylenols and formaldehyde of high dielectric strength and low moisture absorption and is preferably combined in such a manner that products of low viscosity and high penetrating power are obtained. The

product is most particularly intended for use in the manufacture of sheet laminated materials of paper, cloth, etc., useful for electrical insulation and various mechanical structures but is most particularly directed to products of this kind where the requirements are for high dielectric values under adverse conditions of high humidity and heat. Products capable of meeting high electrical tests under these adverse conditions i are highly desirable andof great value under ordinary conditions of use.

This application is a division of my prior application, Serial No. 127,482, filed August 5, 1926, and entitled Synthetic resins and method of making the same.

The xylenols produce condensation prodnets of high reactivity when condensed with an aldehyde, more particularly formaldehyde, without the use of a condensing or catalytic agent. The reaction product made from these phenolic homologues and formal dehyde without the use of a COIldQIlSlllg or catalytic agent gives resinous condensation products of great purity in that no extraneous action on a large commercial scale.. 'When a catalyst is present in the reacting .digester where this reaction is carried out. the final product is un-uniform' in that certain portions of the mass are carried over too far to i give the mostsatisfactory results for this special technical purpose. Where a basic catalyst is used even in small quantities as at' present considered in the art of say one to two per cent of sodium or potassium carbonate or hydroxide, the reaction is extremely I diificult to control and the end product is evidently a mixture of highly reacted or polymerized condensation products with otherproducts still in their uncombined materials need be used to carry out this re- 1 paperlnuung the right absorptive index 1n state or in a relatively loosely combined condition. Where the catalyst is reduced to say .01 of the quantity specified above or .01 to .02 per cent of the Xylenol used the reaction requires precautions when digesting a large quantity of material at a time and there is present this trace of hydrolyzable material which is objectionable in the final infusible product.

Where the reaction between the xylenols and formaldehyde is carried out without the use of condensing agentsthe reaction is carried out with precision and the only precaution necessary is to stop the reaction at the proper point when the materials have been sufliciently combined and when a product of the desired viscosity has been obtained. Objects made from these resins, as for example laminated sheets and hot molded articles containing the well known fillers, have ex tremely low moisture absorption. The low moisture absorption indicates that the resin ly dillieult to-impregnate this material and great precautions are necessary to secure a order that it may be used and that satisfactory physical and electrical values may be obtaine in the laminated structure formed therefrom when impregnatml with the usual phenol or cresol formaldehyde plus alkali condensation products. Although the xylenol is relatively cheap compared to phenol or good grades of meta and para cresol, it is capable of producing condensation products when combined with formaldehyde having. a low viscosity and great penetrating power, and the final-end products are high in dielectrio and mechanical strength, and even in kraft paper the tensile split or the force required to tear the paper, and which is usually termed tensile split is very high. It has been the contention that phenolformaldehyde condensation products made without a catalyst react but slowly as, for example, in-the- Story British Patent No. 8,875 of 1905. Note also paper read by Dr. Baekeland before the New York section of the American Chemical Society on February 5, 1909, and published in the Journal of Industrial & Engineering Chemistry in 1909., volume 1, pages 149 to 161, wherein he speaks of the slow reactivity of Storys product. However, during all this discussion no mention is made that resinous condensation products of phenols or their homologues or more specifically the. Xylenols when reacted with formaldehyde would give products relatively superior in electrical properties than where these materials are made in the presence of a condensing agent. Resinous phenolic condensation products lack many of the good attributes of other insulating materials and much of this deficiency is due to the use of catalysts or condensing agents.

It is true that the reaction between phenol and formaldehyde is quite slow when no condensing agent is used, but for certain purposes it is possible to produce commercial products of very high electrical value, although, of course, the reaction is somewhat slower. On the other hand, for certain purposes the reaction may be speeded by the use of high temperatures.

As will be noted in the examples to be given later, the rate of reaction is greater where the xylenols are used than where phenols are used. This is probably due to the greater solubility of formaldehyde in the xylenols than in phenol, so that the formaldehyde is extracted from the water solution almost at once, which results in a higher concentration of the reacting. components. Furthermore, the higher boiling points of the xylenols, together with the fact that they do not readily steam distill, permits the use of higher temperatures, which, of course, would tend to still further increase the rate of reaction. The reaction is usually carried out in from two to two and one-half hours which is a very convenient duration of time where large commercial batches of material are made. On subsequent impregnation into a sheetlike product such as kraft paper it will be found that the loss in resin' volatile substance is no greater than where a catalyst is used. Upon subsequently pressing the product under the usual temperatures, pressures and duration of time used for the production of products of this type heretofore utilizing materials including catalytic agents, noincreased time is required and the product assumes a hard, infusible, relatively insoluble form having high physical and electrical values.

digester equipped with By my choice of raw material and the carrying of the reaction through its resinous condensation cycle without a catalytic or condensing agent, it is possible to produce a synthetic resin product of xylenols and formaldehyde which has all the reactivity necessary for its use either as a varnish for incorporation iuto textile or paper products or as a solid resin to be ground and incorporated in various paper products at the beaters of the paper mill.

When this material is used for incorporation at the boaters of the paper mill it will be found, likewise, that the Xylenols are much less soluble in water and. that it is not at all necessary to first add additional phenolic bodies to the waters at the heaters in order to obviate the loss of xylenol which may be in a more or less free state within the resinous body. Evidently this has been found a dcsirable practice with certain types of phenolcresol-formaldehyde resins as has been brought out in some of the recent patent art, The elimination of .this step simplifies the process of introducing a resinous product at the heaters of the paper mill as it is only necessary to introduce the proper proportion of this finely ground, comminuted resin at the heaters or thoroughlymix or commingle the same with the paper pulp or furnish. It is also found objectionable to use a hardening agent such as hexamethlycnetetramine, first because the hexamethylenetetramine lib erates large amounts of ammoniaand certain of this ammonia becomes entrapped within the product and some combines with the resin forming a resinate. Secondly, hexamethylenetetramine is readily soluble in water and therefore cannot be introduced at the heaters unless it had previously been combined w ith the resinous product.

\Vhere the product is mixed with the paper pulp at the heaters or in the stuff chest the only precautions necessary are to make sure that the material is properly mixed with the fibres and that when formed in sheetlike form the temperature of the drying rolls or drying tunnels be maintained well below the critical reacting temperature of the resin.

In order that my invention may be better understood, the following example is given by way of illustration E wample Xylenol, commercial grade 32 parts.

Formaldyhyde, commercial grade 37 to 40 per cent strength 21.2 parts.

These materials are placed into a suitable an efficient stirrer and provided with a suitable condenser for distillation. \Vith the condenser set in a distillation angle the product is boiled vigorously. Stirring being maintained during the entire reaction and distillation cycle. There is evidently an immediate combination bein the distillate, moreover, the distillate has practically no formaldehyde odor. It should be noted particularly that no step is called for in this process whereby a refluxing reaction is maintained during any portion of this cycle.

The boiling and distillation is continued for about two hours or for such a length of time and under such conditions of temperature control, etc. until the desired viscosity or combination has been obtained. The reaction goes along smoothly and the removal of both the water of solution and, condensation may be removed with little difliculty at ordinary atmospheric pressure as the reaction product is thin at the early stages of the reaction and as the solubility of water in xylenol is low.

F rom' 15 to 18 parts of distillate will be removed depending on the completeness of the reaction and on the strength of the formaldehyde solution" used. The temperature of the. contents of the digester start boiling at about 212 F. and the temperature increases as the water is eliminated until a temperature of 280 F. is preferably reached. At this temperature the product will be a hard grindable resin. For varnishes and gums an end temperature of from 250 to 270 F. will produce a desirable product. lVith vacuum distillation at the end of the reaction or say after a temperature of 250 F. has been reached a hard resin can be ob- .tained on large batches with less precautions.

Although no refluxing has been carried. out as previously stated there is less loss of reagents than if the reaction were carried out under reflux conditions. Under this method of operation the contact between the two reagents, i.- e., xylenol and formaldehyde, is better because of the elimination of the water of reaction as the condensation progresses.

It will be noted that the proportion of the reagents used as given in this example is approximately in equal molecular proportion and that the resin does not remain permanently fusible, and that,therefore, there is no appreciable loss of formaldehyde when xylenols are used and that no contracting pressure or-reflux-ing is necessary to retain the predetermined amount of reagent proportions.

' So far as the proportion of reagents is concerned a wide variation is possible, that is, an excess of formaldehyde will take care of itself by either a further combination or will be eliminiated duringthe subsequent drying or processing operatioiis, and so far as the, xylenols are concerned they will lilgewise be evaporated or driven ofl so that under proper drying conditions a wider variation in the proportion of the reagent can be used and To this material while still hot and with the condenser set at the reflux position, I add alcohol 24 parts and furfural 2 parts. The

alcohol is added in order to obtain a thin mass which may be readily used for impregnation and additional quantities of alcohol may be added if necessary before the material is used.

To the gums or resins made according to the process disclosures given one or two various hardening agents may be added such as, for example, hexamethylenetetramine, polymerized formaldehyde or various bodies having active methylenegroups in condition to combine with the resinous products or for that matter other aldehydes or their derivatives such as furfural or furfuramid. The product, however, is complete in itself and no hardening agent is necessary unless it be used more in the nature of an accelerating agent in order to promote the speed or lower the temperature at which the reaction is brought to a final infusible form.

The furfural is added for the purpose of acting as a neutral final hardening agent assisting in converting the resinous product upon final pressing to its final hard and in- :fusible form. In the place of furfural a neutral well washed' furfuramid may be added in from one to ten per cent of the weight of the resin solids. This furfuramid, however, where the product is to be used for the highest grade of electrical structure is objectionable as it breaks down to furane, furfural and ammonia. Likewise, hexamethylenetetramine can be used as a hardening agent, but this also isobjectionable because of the ammonia liberated.

The use of a hardening agent is not essential as the material is complete in itself and will upon subsequent heating go to the infusible, substantially insoluble state. There is no objeetion, however, to the use of furfural itself as the product is neutral and will not affect the dielectric thetic resin.

Various coloring materials, dyes, pigments, etc., the dyes preferably soluble in the solvents used and the pigments preferably in properties of the syncolloidal suspension, may be added before,

during or atthe end of the reaction. Various modifying agents maybe added such as camphor, oil of camphor, lanolin, or Chinawood oil. These modifying agents are usually added' through the use of other solvents than, alcohol as, for'example, where lanolin is used this is added in a dissolved state with benzol. Where Chin? wood oil is used this is preferably added by using about twice the weight of the China wood oil in furfural, benzol or carbon tetrachloride. These modifying agents tend to make the material more plastic so it may be more readily machined,

cut, punched, etc., when in the' cold state. Various lubricants may be added such as, for example, a quantity of camphor, stearic acid, or calcium stearate.

Wherein I have called for the use of xylenol it is to be understood that the commercial grade of xylenols include certain lower boiling fractions andcertain higher boiling fractions which are in no way detrimental for my purpose. It is, of course, also evident that the use of xylenols because of their high boiling range and excellent resin solvent properties and tendency to form a gel makes them useful when added in various proportions to other phenolic bodies and therefore, it is to be understood that I wish this use included wherein I claim the use of xylenols.

Wherein I have called for the use of formaldehyde or aqueous solution of formaldehyde it is to be understood that I can use formaldehyde gas or various forms of polymerized formaldehyde or other useful substances having active methylene groups in condition to combine with either the xylenols or the resinous condensation products produced from them. It is, however, to be noted that the intention of this specification is the use of an active methylene body which will not liberate bases or acids whereby the electrical properties of the product would be impaired. Wherein I have shown that the resin is preferably alcohol soluble it is to be understood that this material is soluble' in various other organic solvents such as acetone,-furfural, etc. or a mixture of alcohol and benzol in various proportions or, for that matter, a mixture of benzol and furfural may be used as solvents for this resinous product. The resinous products, on the other hand, may be reacted to the point where they are no longer soluble in alcohol but require certain higher solvents such as, for example, acetone or furfural, or mixtures of these. These resinous products when no longer soluble in alcohol are more highly polymerized and the penetration of varnish solvents may be regulated by the degree of preliminary polymerization.

It is to be understood that these resinous condensation products of xylenols and formaldehydes are soluble in 15% alkaline solutions such as sodium or potassium hydroxide and that they are precipitated out of solution by the use of a suitable quantity of acid or, for that matter, by alum such as ordinarypotassium alum. These resinous products when in suitable form either in solution or in finely comnnnuted particles, may be incorporated with various spun or woven textile or paper' products at the time such products are being formed orat any preferred time thereafter.

. lVhen so combined with these textile products they act as reinforcing cementitious materials which may be subsequently reacted under heat or heat and pressure to their final infusible form. For certain classes of work where solvent recovery is not possible it is preferable to introduce these resinous roducts into these textile or paper products y direct incorporation methods at a considerable saving in solvent cost.

l/Vhile the synthetic resin products made of xylenols or mixtures or other phenolic bodies with xylenol and formaldehyde are particularly well adapted for use in making laminated paper and textile roducts, they are also useful for the manu acture of comminuted molding powders when mixed or incorporated with suitable organic or inorganic i111- ers, plasticizers and modifying agents.

These synthetic resin products when in solution as a varnish mix well with pyroxlin products producing lacquers of a very desirable quality. As the synthetic resin products polyinerize gradually at ordinary room temperature the film of pyroxylin lacquer becomes stronger and tougher with age. The resinous product furthermore leaves a glossy, shiny film, does not weaken, and increases the adhesion of the film to the supporting body. It has an outstanding desirable property in that when used in various quantities and even when used in small quantities it reduces the viscosity of the lacquer to such an extent that a relatively high viscosity nitrocellulose can be used and products of relatively high solids content and low viscosity can be obtained when in solution in suitable solvents. This is particularly true when some of the furfural has, been caused to combine with the xylenol formaldehyde resin but.

the resin without the furfural added will a somewhat lesser extent.

llVhat I claim is- 1. In the art of resin making the step comprising the removal, from the reaction chamber, of the water vapor including the synthetic water vapor of condensation substantially as fast as formed while bringing about a reaction between a phenolic body and a body having active methylene groups whereby a resinous'product is formed.

2. In the art of resin making the step comprisin the removal, from the reaction chamber, 0 water vapor including the synthetic water vapor of condensation substantially as fast as formed while bringing about a reaction between a phenolic body and forma1dehyde whereby a resinous product is formed.

3. In the art of resin making the step comprisin the removal, from the reaction chamber, of the water Va or including the synthetic water vaporo condensation substantially as fast as formed while bringing about a reaction between a-xylenol and a body having active methylene groups whereby a resinous product is formed.

4. In the art of resin making the step compzising the removal, from the reaction chamr, 0 water vapor including the synthetic water vapor of condensation substantially as fast as formed while bringing about a reaction between a body contaming xylenols and formaldehyde whereby a resinous product is formed.

' 5. In the art of resin making the step comprising the removal, from the reaction chamber, of water vapor including the synthetic water vapor of condensation substantially as last asformed While bringing about a reaction between a phenolic body and an active methylene body without the aid of a catalyst, whereby a resinous product is formed.

, 6. In the art of resin making the step comprising the removal, from the reaction chamber, of Water vapor including the synthetic watervapor of condensation substantially as fast as formed while bringing about a reaction between a phenolic body and formaldehyde without the aid of a catalyst, whereby a resinous product is formed.

7. In the art of resin making the step comrising the removal, from the reaction chamer, of the water va or including the synthetic water vapor o condensation substantially as fast as formed while bringing about a reaction between a body containing xylenols with formaldehyde without the aid of a catalyst.

Signed at Philadelphia, in the county of Philadelphia and State of Pennsyglvania, this twenty-seventh dav of July, A. 1927.

A EMIL E. NOVOTNY. 

